1. Field of the Invention
The present invention relates to the technical field of multi-wavelength optical packet switching and, more particularly, to a multi-wavelength optical packet switch system with shared output buffer.
2. Description of Related Art
Currently, signals of multiple channels (wavelengths) in an optical fiber can be transmitted concurrently with the use of wavelength division multiplexing (WDM) technology. Thus, the available bandwidth for a single optical fiber is significantly increased.
Since both data transmission rate and wavelength number transmittable by a single optical fiber are increasingly improved, typical optoelectric transformations for packet switching in optical communication networks are increasingly unsatisfied. To overcome this, U.S. Pat. No. 5,416,769 granted to Karol for a “Controlled-feedback packet switching system” applies a shared buffer to delay the transmission of input packets in accordance with the output conflicts, thereby increasing packet switching efficiency. However, such a configuration can be applied in a one-wavelength packet switching only. For a multi-wavelength optical communication network, the buffer cannot be shared by other wavelengths (channels).
Accordingly, U.S. Pat. No. 5,469,284 granted to Hass for an “Optical packet switch” further applies an input buffer to overcome the aforementioned problem of packet switching efficiency. In such a configuration, delay time for an input packet is determined on a scheduling stage and subsequently the input packet is switched to an appropriate output in a switch stage. However, the input buffer effects the limited improvement and can be applied in a one-wavelength packet switching only. For a multi-wavelength optical communication network, the input buffer cannot be shared by other wavelengths (channels). Besides, it needs a lot of 2×2 optical switches to thus increase much cost.
Accordingly, U.S. Pat. No. 6,519,062 granted to Yoo for an “Ultra-low latency multi-protocol optical routers for the next generation internet” further applies a plurality of shared buffers. In such a configuration, separated wavelengths at each input terminal are fed to a switch at the same time. The switch can be divided into several levels on practical needs, such that the plurality of shared buffers can be used to delay the transmission of packets when the output conflicts are encountered, thereby providing the cited packet switching for a multi-wavelength optical communication network. However, additional I/O ports for two tunable wavelength converters (WCs) and one wavelength router (WR) are required for each additional shared buffer, which significantly increases the cost. Therefore, it is desirable to provide an improved multi-wavelength optical packet switch system to mitigate and/or obviate the aforementioned problems.